Oil cooler having adjustable heat transfer effectiveness

Abstract

An oil cooler is provided for a wall of an air flow passage of a gas turbine engine. The oil cooler has a heat exchanger with an oil conduit for carrying a flow of heated oil proximal to the wall of the air flow passage. The heat exchanger is arranged to transfer heat from the heated oil to the air flowing through the passage. The oil cooler further has a system for altering the flow of air across the heat exchanger such that the heat transfer effectiveness of the heat exchanger can be adjusted.

The invention claimed is: 
     
       1. A gas turbine engine comprising an air flow passage and an oil cooler mounted to a wall of the air flow passage, the oil cooler including:
 a heat exchanger with an oil conduit for carrying a flow of heated oil proximal to the wall of the air flow passage, the heat exchanger being arranged to transfer heat from the heated oil to air flowing through the air flow passage, the heat exchanger being disposed entirely on a side of the wall of the air flow passage that contacts the air flowing through the passage; and 
 a system for altering the flow of air across the heat exchanger, the system including an actuator for changing a position of the heat exchanger relative to the wall of the air flow passage, such that the heat transfer effectiveness of the heat exchanger can be adjusted. 
 
     
     
       2. The gas turbine engine according to  claim 1 , the oil cooler further including at least one temperature sensor, said system being operatively connected to each of the at least one temperature sensor such that said system alters the flow of air across the heat exchanger depending on the temperature sensed by the at least one temperature sensor. 
     
     
       3. The gas turbine engine according to  claim 2 , the oil cooler having at least one temperature sensor which detects the temperature of the oil within the gas turbine engine. 
     
     
       4. The gas turbine engine according to  claim 2 , the oil cooler having at least one temperature sensor which detects the temperature of fuel being sent for combustion by the gas turbine engine. 
     
     
       5. The gas turbine engine according to  claim 2 , wherein said system alters the flow of air across the heat exchanger when the sensed temperature is outside a pre-set range. 
     
     
       6. The gas turbine engine according to  claim 1 , wherein the heat exchanger has a leading edge and a trailing edge relative to the direction of air flowing through the passage, the position of the heat exchanger being changed by moving at least one of the leading or trailing edge. 
     
     
       7. The gas turbine engine according to  claim 1 , wherein the oil cooler further has an inlet duct through which the flow of air arrives at the heat exchanger, and the system comprises a device for changing the amount of flow through the inlet duct to alter the flow of air across the heat exchanger. 
     
     
       8. The gas turbine engine according to  claim 1 , wherein the oil cooler further has an outlet duct through which the flow of air leaves the heat exchanger, and the system comprises a device for changing the amount of flow through the outlet duct to alter the flow of air across the heat exchanger. 
     
     
       9. The gas turbine engine according to  claim 1 , wherein the oil conduit carries the flow of heated oil in a layer substantially parallel to the wall of the air flow passage, the heat exchanger having a plurality of air fins projecting away from the conduit to transfer heat from the oil to the air flowing through the passage. 
     
     
       10. The gas turbine engine according to  claim 1 , wherein the oil cooler has a plurality of said heat exchangers. 
     
     
       11. The gas turbine engine according to  claim 1 , wherein the oil cooler further has one or more additional heat exchangers whose heat transfer effectivenesses are not adjustable. 
     
     
       12. The gas turbine engine according to  claim 1 , wherein the oil cooler is mountable in a fan bypass duct. 
     
     
       13. A method of operating the gas turbine engine of  claim 1 , the method comprising the step of: altering the flow of air across the heat exchanger to adjust the heat transfer effectiveness of the heat exchanger. 
     
     
       14. The gas turbine engine according to  claim 1 , wherein the actuator is configured to change a spacing between at least a part of the heat exchanger and the wall of the air flow passage. 
     
     
       15. The gas turbine engine according to  claim 1 , wherein the oil cooler has a leading edge and a trailing edge relative to the direction of air flowing through the passage, and the actuator is configured to change the position of the heat exchanger by moving only the leading edge. 
     
     
       16. The gas turbine engine according to  claim 1 , wherein the air flow passage is configured such that air flowing through the passage only contacts the side of the wall on which the heat exchanger is disposed. 
     
     
       17. A gas turbine engine comprising an air flow passage and an oil cooler mounted to a wall of the air flow passage, the oil cooler including:
 at least one temperature sensor; 
 a heat exchanger with an oil conduit for carrying a flow of heated oil proximal to the wall of the air flow passage, the heat exchanger being arranged to transfer heat from the heated oil to air flowing through the air flow passage, the heat exchanger being disposed entirely on a side of the wall of the air flow passage that contacts the air flowing through the passage; and 
 a system for altering the flow of air across the heat exchanger, the system including an actuator for changing a position of the heat exchanger relative to the wall of the air flow passage, such that the heat transfer effectiveness of the heat exchanger can be adjusted, the system being operatively connected to each of the at least one temperature sensor such that said system alters the flow of air across the heat exchanger depending on the temperature sensed by the at least one temperature sensor.